You can use regular laundry detergent in your high efficiency washing machine if you want too but it's not recommended since regular detergent will create too many soap suds which will not rinse out of your laundry and clothes as good with the high efficiency washing machine.
The regular detergent in a high efficiency washing machine will also not get your clothes as clean as it would in a regular washing machine due to the detergent creating too many soap suds.
Laundry detergent made for high efficiency washing machines is made to not create as many suds as normal laundry detergent so it's important to use soap made specifically for high efficiency washing machines to make your high efficiency washing machine work and clean the clothes and laundry like it was made to do.